Featured Research

from universities, journals, and other organizations

Radar Finds Evidence For Hydrocarbon Lakes On Saturn's Moon Titan

Date:

October 6, 2003

Source:

Cornell University

Summary:

The smog-shrouded atmosphere of Titan, Saturn's largest moon, has been parted by Earth-based radar to reveal the first evidence of liquid hydrocarbon lakes on its surface. The observations are reported by a Cornell University-led astronomy team working with the world's largest radio/radar telescope at the National Science Foundation's (NSF) Arecibo Observatory.

Share This

The smog-shrouded atmosphere of Titan, Saturn's largest moon, has been parted by Earth-based radar to reveal the first evidence of liquid hydrocarbon lakes on its surface. The observations are reported by a Cornell University-led astronomy team working with the world's largest radio/radar telescope at the National Science Foundation's (NSF) Arecibo Observatory.

Related Articles

The radar observations, reported in the journal Science on its Science Express Web site (Oct. 2, 2003), detected specular -- or mirrorlike -- glints from Titan with properties that are consistent with liquid hydrocarbon surfaces. Cornell astronomer Donald Campbell, who led the observation team, does not rule out that the reflections could be from very smooth solid surfaces. "The surface of Titan is one of the last unstudied parcels of real estate in the solar system, and we really know very little about it," he says.

The observations were made possible by the 1997 upgrade of the telescope's 305-meter (1,000 feet) diameter dish, which has greatly increased the sensitivity of what was already the world's most powerful radar system. The observatory is managed by the National Astronomy and Ionosphere Center (NAIC), based at Cornell in Ithaca, N.Y., which has been operating the huge telescope for the NSF since 1971.

Campbell, who is associate director of NAIC as well as a Cornell professor of astronomy, notes that for more than two decades astronomers have speculated that the interaction of the sun's ultraviolet radiation with methane in Titan's upper atmosphere -- photochemical reactions similar to those that cause urban smog -- could have resulted in large amounts of liquid and solid hydrocarbons raining onto Titan's frigid surface (minus 290 degrees Fahrenheit, or minus 179 degrees Celsius). Campbell explains that radar signals would specularly reflect -- or glint -- from liquid surfaces on Titan, similar to sunlight glinting off the ocean. Although Titan's underlying surface is thought to be water ice, the complex chemistry in the upper atmosphere might have resulted in the icy surface being at least partly covered in liquid ethane and methane and solid hydrocarbons, says Campbell. One class of the solid hydrocarbons, often referred to as Titan tholins, was artificially created in a campus laboratory by a team led by the late Cornell astronomer Carl Sagan.

Titan, which is about 50 percent larger than the Earth's moon, is the only satellite in the solar system with a dense atmosphere. This atmosphere is transparent to radio/radar waves and partially transparent at short infrared wavelengths but is opaque at visible wavelengths.

The observations were made in November and December of both 2001 and 2002. The radar signal takes 2.25 hours to travel to Titan and back. The Arecibo radar operates at a 13-centimeter wavelength (2,380 megahertz), and the transmitted power is close to one megawatt (the equivalent of about 1,000 microwave ovens). Both the Arecibo telescope and the NSF's new 100-meter Robert C. Byrd Green Bank Telescope were used to receive the extremely weak radar echoes.

Next summer, NASA's Cassini spacecraft, launched in 1997, is scheduled to go into orbit around Saturn and its moons for four years. The piggybacking Huygens probe is scheduled to plunge into the hazy Titan atmosphere and land on the moon's surface.

On Campbell's team for the Arecibo radar observations of Titan were Gregory Black, the University of Virginia; Lynn Carter, Cornell graduate student; and Steven Ostro, Jet Propulsion Laboratory.

The Arecibo Observatory part of NAIC which is operated by Cornell University under a cooperative agreement with the NSF. NASA provides partial support for Arecibo's planetary radar program. The Robert C. Byrd Green Bank Telescope is part of the National Radio Astronomy Observatory, an NSF supported institution operated under cooperative agreement by Associated Universities Inc.

More From ScienceDaily

More Space & Time News

Featured Research

Mar. 31, 2015 — Astronomers have conducted observations of the massive-star forming region IRAS 16547-4247. The observation results shows the presence of multiple, or at least two, gas outflows from a protostar, ... full story

Mar. 30, 2015 — Observations made with two space observatories, Herschel and Planck, reveal glimpses into how today's galaxies came to be. Using one-of-a-kind instrumentation, astronomers were able to study large ... full story

Mar. 30, 2015 — Stars form when gravity pulls together material within giant clouds of gas and dust. But gravity isn't the only force at work. Both turbulence and magnetic fields battle gravity, either by stirring ... full story

Mar. 30, 2015 — Scientists have long puzzled over the planet Mercury's excessively dark surface. New research suggests that carbon from passing comets could be the planet's mystery darkening ... full story

Mar. 30, 2015 — Luke Skywalker's home in "Star Wars" is the desert planet Tatooine, with twin sunsets because it orbits two stars. So far, only uninhabitable gas-giant planets have been identified circling such ... full story

Mar. 26, 2015 — Astronomers have studied how dark matter in clusters of galaxies behaves when the clusters collide. The results show that dark matter interacts with itself even less than previously thought, and ... full story

Mar. 26, 2015 — The best observations so far of the dusty gas cloud G2 confirm that it made its closest approach to the supermassive black hole at the centre of the Milky Way in May 2014 and has survived the ... full story

Mar. 25, 2015 — Researchers have completed a new analysis of an ancient Martian lake system in Jezero Crater, near the planet's equator. The study finds that the onslaught of water that filled the crater was one of ... full story

Mar. 25, 2015 — The precise measurement of Saturn's rotation has presented a great challenge to scientists, as different parts of this sweltering ball of hydrogen and helium rotate at different speeds whereas its ... full story

Related Stories

Mar. 9, 2015 — Recently, by combining the highly sensitive receiving capabilities of the National Science Foundation's Green Bank Telescope and the powerful radar transmitter at the NSF's Arecibo ... full story

Mar. 5, 2014 — Ten years ago, we knew Titan as a fuzzy orange ball about the size of Mercury. We knew it had a nitrogen atmosphere -- the only known world with a thick nitrogen atmosphere besides Earth. But what ... full story

Apr. 15, 2013 — By tracking a part of the surface of Saturn's moon Titan over several years, NASA's Cassini mission has found a remarkable longevity to the hydrocarbon lakes on the moon's ... full story

Jan. 8, 2013 — It's not exactly icing on a cake, but it could be icing on a lake. A new paper by scientists on NASA's Cassini mission finds that blocks of hydrocarbon ice might decorate the surface of ... full story

Sep. 21, 2010 — Titan, one of Saturn's moons, is the only moon in the solar system with an atmosphere -- ten times denser than the atmosphere of Earth. Five years ago, the Cassini-Huygens mission to Saturn sent ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.